From: Roman Perepelitsa <roman.perepelitsa@gmail.com>
To: Felipe Contreras <felipe.contreras@gmail.com>
Cc: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: Bug with unset variables
Date: Thu, 12 Nov 2020 20:10:57 +0100 [thread overview]
Message-ID: <CAN=4vMoPrb3EVmM7T57DpPvWYdndHdiwhqpi-V+5JgGVbdh8qQ@mail.gmail.com> (raw)
In-Reply-To: <CAMP44s09or4ZtTiPW8yz8K+jpVqFKQVZtQnNUfA0zVda5zFH-g@mail.gmail.com>
On Thu, Nov 12, 2020 at 7:47 PM Felipe Contreras
<felipe.contreras@gmail.com> wrote:
>
> This is distinction without a difference, like saying we are not lost,
> we just don't know where we are. Conceptually it is the same thing,
> you are just using a different word for it. It's wordplay.
>
> An unset variable is for all intents and purposes a variable with a null value.
Only in languages where variables cannot have null values, and only
because you can declare "null" to be a synonym for "unset" in this
case.
> JavaScript
In JavaScript you unset a variable with `delete foo` and you assign it
a "null" value (in quotes because javascript has another null) with
`foo = undefined`. These are not equivalent.
Note that these two snippets have different effect:
var foo
and
var foo
delete foo
Just line in zsh, and unlike ksh/bash.
> Python
Same thing but `del var` and `var = None`.
Et cetera. ksh and bash are rather exceptional in this regard.
Roman.
next prev parent reply other threads:[~2020-11-12 19:11 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 15:57 Felipe Contreras
2020-11-11 16:13 ` Roman Perepelitsa
2020-11-11 16:56 ` Felipe Contreras
2020-11-11 17:02 ` Roman Perepelitsa
2020-11-11 18:03 ` Felipe Contreras
2020-11-11 18:16 ` Roman Perepelitsa
2020-11-11 20:42 ` Felipe Contreras
2020-11-12 0:20 ` Mikael Magnusson
2020-11-12 1:10 ` Felipe Contreras
2020-11-12 8:45 ` Roman Perepelitsa
2020-11-12 10:47 ` Peter Stephenson
2020-11-12 18:48 ` Bart Schaefer
2020-11-12 19:49 ` Felipe Contreras
2020-11-12 18:46 ` Felipe Contreras
2020-11-12 19:10 ` Roman Perepelitsa [this message]
2020-11-12 21:08 ` Felipe Contreras
2020-11-13 8:51 ` Roman Perepelitsa
2020-11-14 0:52 ` Felipe Contreras
2020-11-14 5:41 ` Roman Perepelitsa
2020-11-16 19:41 ` Felipe Contreras
2020-11-16 20:22 ` Roman Perepelitsa
2020-11-17 20:28 ` Felipe Contreras
2020-11-18 22:45 ` Daniel Shahaf
2020-11-22 1:20 ` Felipe Contreras
2020-11-23 4:00 ` Daniel Shahaf
2020-11-23 6:18 ` Felipe Contreras
2020-11-19 2:59 ` Bart Schaefer
2020-11-22 1:50 ` Felipe Contreras
2020-11-17 20:54 ` Bart Schaefer
2020-11-22 1:49 ` Felipe Contreras
2020-11-23 6:48 ` Bart Schaefer
2020-11-23 7:26 ` Felipe Contreras
2020-11-23 20:26 ` Bart Schaefer
2020-11-23 23:39 ` Felipe Contreras
2020-11-24 0:52 ` Bart Schaefer
2020-11-25 8:46 ` Felipe Contreras
2020-11-27 15:44 ` Daniel Shahaf
2020-11-27 20:49 ` Felipe Contreras
2020-11-27 20:59 ` Daniel Shahaf
2020-11-27 21:33 ` Bart Schaefer
2020-11-27 23:37 ` Daniel Shahaf
2020-11-27 23:45 ` Bart Schaefer
2020-11-28 0:24 ` Bart Schaefer
2020-11-28 7:32 ` Bart Schaefer
2020-11-28 12:05 ` Felipe Contreras
2020-11-12 19:26 ` Bart Schaefer
2020-11-12 21:48 ` Felipe Contreras
2020-11-13 22:17 ` Bart Schaefer
2020-11-14 0:58 ` Felipe Contreras
2020-11-11 18:36 ` Bart Schaefer
2020-11-11 21:08 ` Felipe Contreras
2020-11-11 17:02 ` Peter Stephenson
2020-11-11 18:05 ` Felipe Contreras
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